MySQLi example

$nr = 0;  // replace this with your existing code


$sql = 'INSERT INTO %s(nr, mailadress, pnr) VALUES (?, ?, ?)';
$utskick = mysqli_prepare($db, sprintf($sql, 'utskick'));
$yahooadr = mysqli_prepare($db, sprintf($sql, 'yahooadr'));

while ($rad = mysqli_fetch_row($result)) {
    $stmt = strpos($rad[0], 'yahoo') !== false ? $yahooadr : $utskick;
    mysqli_execute($stmt, [$nr, $rad[0], $rad[1]]);
    $nr++;
}